Wireless power interface and device

ABSTRACT

A wireless power interface includes first coil, a plurality of coils, and a control module. Each of the plurality of coils has a different orientation with respect to at least one axis of a multi-dimensional axis system. The control module is configured to enable at least one of the plurality of coils based on electro-magnetic coupling between the first coil and the at least one of the plurality of coils such that power is derived via the electro-magnetic coupling.

CROSS REFERENCE TO RELATED PATENTS

The present U.S. Utility Patent Application claims priority pursuant to35 U.S.C. §120, as a continuation, to the following U.S. Utility PatentApplication which is hereby incorporated herein by reference in itsentirety and made part of the present U.S. Utility Patent Applicationfor all purposes:

1. U.S. Utility application Ser. No. 13/181,976, entitled “WIRELESSPOWER INTERFACE AND DEVICE,” (Attorney Docket No. BP5465C2), filed Jul.13, 2011, pending, which claims priority pursuant to 35 U.S.C. §120, asa continuation, to the following U.S. Utility Patent Application whichis hereby incorporated herein by reference in its entirety and made partof the present U.S. Utility Patent Application for all purposes:

2. U.S. Utility application Ser. No. 12/839,296, entitled “RFIDINTERFACE AND APPLICATIONS THEREOF,” (Attorney Docket No. BP5465C1),filed Jul. 19, 2010, now issued Jul. 26, 2011, as U.S. Pat. No.7,986,240, which claims priority pursuant to 35 U.S.C. §120, as acontinuation, to the following U.S. Utility Patent Application which ishereby incorporated herein by reference in its entirety and made part ofthe present U.S. Utility Patent Application for all purposes:

3. U.S. Utility application Ser. No. 11/494,149, entitled “RFIDINTERFACE AND APPLICATIONS THEREOF,” (Attorney Docket No. BP5465), filedJul. 26, 2006, now issued Jul. 20, 2010 as U.S. Pat. No. 7,760,093.

TECHNICAL FIELD

This invention relates generally to communication systems and moreparticularly to wireless power conveyance.

DESCRIPTION OF RELATED ART

A wireless power system generally includes a reader, also known as aninterrogator, and a remote tag, also known as a transponder. Each tagstores identification data for use in identifying a person, article,parcel or other object. Wireless power systems may use active tags thatinclude an internal power source, such as a battery, and/or passive tagsthat do not contain an internal power source, but generate power fromradio frequency (RF) signals received from a reader.

In general, to access the identification data stored on RFID tags, theRFID reader generates a modulated RF interrogation signal designed toevoke a modulated RF response from the tag. The RF response from the tagincludes the coded identification data stored on the RFID tag. The RFIDreader decodes the coded identification data to identify the person,article, parcel or other object associated with the RFID tag. Forpassive tags, the RFID reader may also generate an unmodulated,continuous wave (CW) signal from which the passive tag derives itspower.

Wireless power systems typically employ either far-field technology, inwhich the distance between the reader and the tag is great compared tothe wavelength of the carrier signal, or near-field technology, in whichthe operating distance is less than one wavelength of the carriersignal. In far-field applications, the RFID reader generates andtransmits an RF signal via an antenna to all tags within range of theantenna. One or more of the tags that receive the RF signal responds tothe reader using a backscattering technique in which the tags modulateand reflect the received RF signal. In near-field applications, the RFIDreader and tag communicate via mutual inductance between correspondingreader and tag inductors.

In wireless power systems that include passive tags, a passive tag'sability to generate power from a received RF signal and/or a mutualinductance signal (hereinafter collectively referred to as an RFIDsignal) directly correlates to the power level at which the tag receivesthe signal. The power level of the RFID signal is maximized when thereader and tag have an ideal orientation. For example, for near-fieldapplications, an ideal orientation occurs when the inductor of thereader is parallel to the inductor of the tag. In many near-fieldapplications, however, the reader is a handheld device that is swipedproximal to the tag. In such instances, the ideal orientation is rarelyachieved and, as the orientation approaches perpendicular, less and lessenergy is transferred from the reader's inductor to the tag's inductor.

Therefore, a need exists for a wireless power interface that providesimproved energy transfer between the reader and the tag.

BRIEF DESCRIPTION OF THE DRAWING(S)

FIG. 1 is a schematic block diagram of an RFID system in accordance withthe present invention;

FIG. 2 is a schematic block diagram of an RFID reader in accordance withthe present invention;

FIG. 3 is a schematic block diagram of an RFID reader and an RFID tag inaccordance with the present invention;

FIG. 4 is a diagram of an RFID reader coil and an RFID tag coil inaccordance with the present invention;

FIG. 5 is a diagram of electro-magnetic coupling between an RFID readercoil and an RFID tag coil in accordance with the present invention;

FIG. 6 is another diagram of electro-magnetic coupling between an RFIDreader coil and an RFID tag coil in accordance with the presentinvention;

FIG. 7 is a diagram of an RFID tag coil with respect to amulti-dimensional axis system in accordance with the present invention;

FIG. 8 is a diagram of a plurality of coils of an RFID reader inaccordance with the present invention;

FIG. 9 is another diagram of a plurality of coils of an RFID reader inaccordance with the present invention; and

FIG. 10 is a schematic block diagram of an embodiment of a wirelesspower interface in accordance with the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of an RFID (radio frequencyidentification) system that includes a computer/server 12, a pluralityof RFID readers 14-18 and a plurality of RFID tags 20-30. The RFID tags20-30 may each be associated with a particular object for a variety ofpurposes including, but not limited to, tracking inventory, trackingstatus, location determination, assembly progress, et cetera.

Each RFID reader 14-18 wirelessly communicates with one or more RFIDtags 20-30 within its coverage area. For example, RFID reader 14 mayhave RFID tags 20 and 22 within its coverage area, while RFID reader 16has RFID tags 24 and 26 and RFID reader 18 has RFID tags 28 and 30within their respective coverage areas. The RF communication schemebetween the RFID readers 14-18 and RFID tags 20-30 may be abackscattering technique whereby the RFID readers 14-18 provide energyto the RFID tags via an RFID signal. The RFID tags derive power from theRF signal and respond on the same RF carrier frequency with therequested data.

In this manner, the RFID readers 14-18 collect data as may be requestedfrom the computer/server 12 from each of the RFID tags 20-30 within itscoverage area. The collected data is then conveyed to computer/server 12via the wired or wireless connection 32 and/or via the peer-to-peercommunication 34. In addition, and/or in the alternative, thecomputer/server 12 may provide data to one or more of the RFID tags20-30 via the associated RFID reader 14-18. Such downloaded informationis application dependent and may vary greatly. Upon receiving thedownloaded data, the RFID tag would store the data in a non-volatilememory.

As indicated above, the RFID readers 14-18 may optionally communicate ona peer-to-peer basis such that each RFID reader does not need a separatewired or wireless connection 32 to the computer/server 12. For example,RFID reader 14 and RFID reader 16 may communicate on a peer-to-peerbasis utilizing a back scatter technique, a wireless LAN technique,and/or any other wireless communication technique. In this instance,RFID reader 16 may not include a wired or wireless connection 32 tocomputer/server 12. Communications between RFID reader 16 andcomputer/server 12 are conveyed through RFID reader 14 and the wired orwireless connection 32, which may be any one of a plurality of wiredstandards (e.g., Ethernet, fire wire, et cetera) and/or wirelesscommunication standards (e.g., IEEE 802.11x, Bluetooth, et cetera).

As one of ordinary skill in the art will appreciate, the RFID system ofFIG. 1 may be expanded to include a multitude of RFID readers 14-18distributed throughout a desired location (for example, a building,office site, et cetera) where the RFID tags may be associated withequipment, inventory, personnel, et cetera. Note that thecomputer/server 12 may be coupled to another server and/or networkconnection to provide wide area network coverage.

FIG. 2 is a schematic block diagram of an RFID reader 14-18 thatincludes an integrated circuit 56 and may further include a local areanetwork (LAN) connection module 54. The integrated circuit 56 includes atransmit section 45, and interface 46, and a receive section 55. Thetransmit section 45 includes a portion of a protocol processing module40, an encoding module 42, and a digital-to-analog converter (DAC) 44.The receive section 55 includes a digitization module 48, a pre-decodemodule 50, a decode module 52, and a portion of the protocol processingmodule 40. The local area network connection module 54 may include oneor more of a wireless network interface (e.g., 802.11n.x, Bluetooth, etcetera) and/or a wired communication interface (e.g., Ethernet, firewire, et cetera).

The protocol processing module 40 is operably coupled to prepare datafor encoding via the encoding module 42 which may perform a dataencoding in accordance with one or more RFID standardized protocols. Theencoded data is provided to the digital-to-analog converter 44 whichconverts the digitally encoded data into an analog signal. The RFIDinterface includes an RFID front-end, a plurality of coils, and acontrol module. The RFID front-end modulates the analog signal toproduce an RF signal at a particular carrier frequency, which istransmitted to an RFID tag via one or more of the plurality of coils.

The RF front-end includes transmit blocking capabilities such that theenergy of the transmit signal does not substantially interfere with thereceiving of a backscattered RF signal received from one or more RFIDtags via one or more of the plurality of coils. The RF front-endconverts the received RF signal into a baseband signal. The digitizationmodule 48, which may be a limiting module or an analog-to-digitalconverter, converts the received baseband signal into a digital signal.The pre-decode module 50 converts the digital signal into a biphaseencoded signal or mixed signal in accordance with the particular RFIDprotocol being utilized. The biphase encoded or mixed signal is providedto the decoding module 52, which recaptures data therefrom in accordancewith the particular encoding scheme of the selected RFID protocol. Theprotocol processing module 40 provides the recovered data to the serverand/or computer via the local area network connection module 54. As oneof ordinary skill in the art will appreciate, the RFID protocols (suchas EPC class 0, EPC class 1, EPC Class 1 Gen 2, ISO 18000-6, etc.)utilize one or more of line encoding schemes such as Manchesterencoding, FM0 encoding, FM1 encoding, four-interval bit cell encoding,etc.

FIG. 3 is a schematic block diagram of an RFID reader 14-18 and an RFIDtag 20-30. In this illustration, the RFID reader 14-18 includes acontrol module 66 and a plurality of coils 64 of the interface 46,operable to derive power via an electro-magnetic coupling, and the RFIDtag includes a coil 62. Each of the plurality of coils has a differentorientation with respect to at least one axis of a multi-dimensionalaxis system.

As shown, one coil has a −45° orientation with respect to an axisperpendicular to the figure, another coil has a 0° orientation withrespect to an axis perpendicular to the figure, and a third coil has a+45° orientation with respect to an axis perpendicular to the figure.

As the RFID reader 14-18 is passed over the RFID tag 20-30, the controlmodule 66 enables at least one of the plurality of coils 62 based onelectro-magnetic coupling 68 between coil 62 and the least one of theplurality of coils 64. In one embodiment, the control module 66 enablesthe at least one of the plurality of coils 64 by providing a transmitsignal (e.g., the output of the DAC 44) to one of the plurality of coils(e.g., the coil with the −45° orientation). The control module 66 thenmeasures a response from the coil 62 via the enabled coil. Such aresponse may be a proprietary signal indicating the receipt of thetransmit signal and/or the power level of the received transmit signal.In another embodiment, the response may be a backscatter signal inaccordance with one or more RFID standards.

The control module 66 then compares the response with a responsethreshold. Such a comparison may include determining that a response wasreceived within a given time frame. If a response is not received withinthe given time frame, it is deemed to have compared unfavorably with theresponse threshold. If a response is received within the given timeframe, its power level and/or error rate is compared to a correspondingpower level and/or error rate threshold.

If the response compares favorably with the response threshold, thecontrol module 66 utilizes the coil for RFID communications between theRFID tag 20-30 and the RFID reader 14-18. If, however, the responsecompares unfavorably with the response threshold, the control module 66then determines whether each of the plurality of coils 66 has beentested. If all of the coils have been tested and none have comparedfavorably to the response threshold, then the control module 66generates an error message or some other indication that anelectro-magnetic coupling between the RFID reader 14-18 and the RFID tag20-30 was not established.

When each of the plurality of coils has not been tested, the controlmodule 66 repeats the preceding steps for another one of the pluralityof coils 66 (e.g., the coil with the −45° orientation). In this manner,the RFID reader 14-18 does not have to be perpendicular to the RFID tag20-30 to get an acceptable level of electro-magnetic coupling 68. Asshown, the RFID reader 14-18 may be at a +/−45° angle and still achievean acceptable level of electro-magnetic coupling 68. In this example,with three coils associated with the RFID reader 14-18, the RFID reader14-18 may be at a severe angle with respect to the RFID tag 20-30 andstill achieve an acceptable level of electro-magnetic coupling 68. Asone of ordinary skill in the art will appreciate, the RFID 14-18 mayinclude more than three coils and have coils with different axialorientations.

In another embodiment, the control module 66 enables the at least one ofthe plurality of coils 66 by providing a transmit signal to a first setof the plurality of coils. In this embodiment, the coils of the firstset are positioned such that the magnetic fields created by the coil ofthe first set have minimal interference with each other. The controlmodule 66 then measures a response from the coil 62 via the first set ofthe plurality of coils. The control module 66 then compares the responsewith a response threshold as previously described.

If the response compares favorably with the response threshold, thecontrol module 66 utilizes the first set of the plurality of coils forthe RFID communications between the RFID tag and the RFID reader. If,however, the response compares unfavorably with the response threshold,the control module 66 repeats the preceding steps for a second set ofthe plurality of coils, where the magnetic fields created by the coil ofthe first set have minimal interference with each other. Note that for anear field RFID communication, the control module enables the at leastone of the plurality of coils as a winding of a transformer, where thecoil 62 of the RFID tag is the other winding of the transformer. Furthernote that for a far field RFID communication, the control module enablesthe at least one of the plurality of coils as an antenna to a transmitcircuit (e.g., transmit section 45) and a receive circuit (e.g., receivesection 55).

FIG. 4 is a diagram of an RFID reader coil 64 and an RFID tag coil 62.The RFID tag coil 62 includes at least one planer winding of a firstgeometry (e.g., a square, rectangle, oval, circle, hexagon, octagon,and/or any combination thereof) and of a first size. Note that the sizeof the coil 62 will depend on the frequency of operation, a desiredpower level, IC fabrication process, printed circuit board (PCB)fabrication process, and/or desired inductance. The RFID reader coil 64,and the other coils of the interface 46, includes at least one planerwinding of the first geometry and of a second size. Note that the RFIDreader coil 64 will typically be larger than the RFID tag coil 62.

In this example, the RFID reader coil 64 is shown as a single windingfor ease of illustration but could include one or more windings on oneor more surfaces of the supporting substrate (e.g., IC or PCB). The RFIDcoil 64 is also shown to be conducting current 70 and thus producing anelectro-magnetic field 72. With the RFID tag coil 62 in a proximallocation and substantially parallel to RFID reader coil 64, theelectro-magnetic field 72 electro-magnetically couples the RFID tag coil62 to the RFID reader coil 64. This is further illustrated in FIG. 5.

FIG. 5 is a diagram of electro-magnetic coupling 68 between the RFIDreader coil 64 and the RFID tag coil 62. In this diagram, the coils 62and 64 are parallel, thus the optimal level of electro-magnetic couplingis obtained. However, if the coils 62 and 64 are not parallel, as shownin FIG. 6, the electro-magnetic coupling is less than optimal. Thus, byhaving a plurality of coils in the RFID reader with differentorientations, it is likely that one or more coils will provide a nearoptimal level of electro-magnetic coupling or, at a minimum, provide anacceptable level of electro-magnetic coupling.

FIG. 7 is a diagram of an RFID tag coil 62 with respect to amulti-dimensional axis system (e.g., X, Y, Z coordinate system). Notethat in this example, the RFID tag coil 62 is shown as a single windingfor ease of illustration but could include one or more windings on oneor more surfaces of the supporting substrate (e.g., IC or PCB).

FIG. 8 is a diagram of a plurality of coils 64 of an RFID reader withrespect to the multi-dimensional axis system of FIG. 7. In thisillustration, each of the plurality of coils 64 has a different axialorientation with respect to the X-Y plane of the multi-dimensional axissystem.

FIG. 9 is another diagram of a plurality of coils 64 of an RFID readerwith respect to the multi-dimensional axis system of FIG. 7. In thisillustration, each of the plurality of coils 64 has a different axialorientation with respect to the Y-Z plane of the multi-dimensional axissystem. Note that the plurality of coils 64 may include more or lesscoils than shown in FIGS. 8 and 9 and may include both sets of coils ofFIGS. 8 and 9. In this latter case, the RFID reader may be misaligned intwo dimensions and still achieve a near optimal level ofelectro-magnetic coupling or, at a minimum, achieve an acceptable levelof electro-magnetic coupling.

FIG. 10 is a schematic block diagram of an embodiment of a interface 46operable to derive power via the electro-magnetic coupling. Theinterface 46 includes the control module 66, the plurality of coils 64,and a switching network 82. In this embodiment, the switching network 82receives a transmit signal 80 from the DAC 44. The control module 66controls the switching network 82, which may be a plurality of switches,transistors, tri-state devices or a combination thereof, to provide thetransmit signal 80 to one or more of the coils 64. In addition, when aresponse is received from coil 62 via the enabled one or more coils 64,the control module 66 receives the response from the switching network.The control module 66 may control the switching network 82 to providethe transmit signal 80 to the plurality of coils 64 as previouslydescribed with reference to FIG. 3.

As may be used herein, the terms “substantially” and “approximately”provides an industry-accepted tolerance for its corresponding termand/or relativity between items. Such an industry-accepted toleranceranges from less than one percent to fifty percent and corresponds to,but is not limited to, component values, integrated circuit processvariations, temperature variations, rise and fall times, and/or thermalnoise. Such relativity between items ranges from a difference of a fewpercent to magnitude differences. As may also be used herein, theterm(s) “coupled to” and/or “coupling” and/or includes direct couplingbetween items and/or indirect coupling between items via an interveningitem (e.g., an item includes, but is not limited to, a component, anelement, a circuit, and/or a module) where, for indirect coupling, theintervening item does not modify the information of a signal but mayadjust its current level, voltage level, and/or power level. As mayfurther be used herein, inferred coupling (i.e., where one element iscoupled to another element by inference) includes direct and indirectcoupling between two items in the same manner as “coupled to”. As mayeven further be used herein, the term “operable to” indicates that anitem includes one or more of power connections, input(s), output(s),etc., to perform one or more its corresponding functions and may furtherinclude inferred coupling to one or more other items. As may stillfurther be used herein, the term “associated with”, includes directand/or indirect coupling of separate items and/or one item beingembedded within another item. As may be used herein, the term “comparesfavorably”, indicates that a comparison between two or more items,signals, etc., provides a desired relationship. For example, when thedesired relationship is that signal 1 has a greater magnitude thansignal 2, a favorable comparison may be achieved when the magnitude ofsignal 1 is greater than that of signal 2 or when the magnitude ofsignal 2 is less than that of signal 1.

The present invention has also been described above with the aid ofmethod steps illustrating the performance of specified functions andrelationships thereof. The boundaries and sequence of these functionalbuilding blocks and method steps have been arbitrarily defined hereinfor convenience of description. Alternate boundaries and sequences canbe defined so long as the specified functions and relationships areappropriately performed. Any such alternate boundaries or sequences arethus within the scope and spirit of the claimed invention.

The present invention has been described above with the aid offunctional building blocks illustrating the performance of certainsignificant functions. The boundaries of these functional buildingblocks have been arbitrarily defined for convenience of description.Alternate boundaries could be defined as long as the certain significantfunctions are appropriately performed. Similarly, flow diagram blocksmay also have been arbitrarily defined herein to illustrate certainsignificant functionality. To the extent used, the flow diagram blockboundaries and sequence could have been defined otherwise and stillperform the certain significant functionality. Such alternatedefinitions of both functional building blocks and flow diagram blocksand sequences are thus within the scope and spirit of the claimedinvention. One of average skill in the art will also recognize that thefunctional building blocks, and other illustrative blocks, modules andcomponents herein, can be implemented as illustrated or by discretecomponents, application specific integrated circuits, processorsexecuting appropriate software and the like or any combination thereof.

1. A wireless power interface comprises: a first coil of a firstwireless power device; a plurality of coils of a second wireless powerdevice, wherein each of the plurality of coils having an orientationsubstantially aligned to a respective axis of a multi-dimensional axissystem; and a control module configured to enable at least one of theplurality of coils based on electro-magnetic coupling between the firstcoil of the first wireless power device and the at least one of theplurality of coils of the second wireless power device.
 2. The wirelesspower interface of claim 1 comprises: the first coil including at leastone planer winding of a first geometry and of a first size; and eachcoil of the plurality coils including at least one planer winding of thefirst geometry and of a second size.
 3. The wireless power interface ofclaim 1, wherein the control module is configured to enable the at leastone of the plurality of coils based on the electro-magnetic couplingbetween the first coil and the at least one of the plurality of coilsby: providing a transmit signal to one of the plurality of coils;measuring a response from the first coil via the at least one of theplurality of coils; comparing the response with a response threshold;when the response compares favorably with the response threshold,utilizing the at least one of the plurality of coils to derive power viathe electro-magnetic coupling; when the response compares unfavorablywith the response threshold, determining whether each of the pluralityof coils has been tested; and when each of the plurality of coils hasnot been tested, repeating the providing, the measuring, and thecomparing for another one of the plurality of coils.
 4. The wirelesspower interface of claim 1, wherein the control module is configured toenable the at least one of the plurality of coils based onelectro-magnetic coupling between the first coil and the at least one ofthe plurality of coils by: providing a transmit signal to a first set ofthe plurality of coils, wherein an electro-magnetic field created by acoil of the first set of the plurality of coils has minimal interferencewith an electro-magnetic field created by another coil of the first setof the plurality of coils; measuring a response from the first coil viathe first set of the plurality of coils; comparing the response with aresponse threshold; when the response compares favorably with theresponse threshold, utilizing the first set of the plurality of coils toderive power via the electro-magnetic coupling; and when the responsecompares unfavorably with the response threshold, repeating theproviding, the measuring, and the comparing for a second set of theplurality of coils, wherein an electro-magnetic field created by a coilof the second set of the plurality of coils has minimal interferencewith an electro-magnetic field created by another coil of the second setof the plurality of coils.
 5. The wireless power interface of claim 1,wherein the control module is configured to enable the at least one ofthe plurality of coils based on the electro-magnetic coupling betweenthe first coil and the at least one of the plurality of coils by:coupling the at least one of the plurality of coils as a winding of atransformer to a transmit circuit and a receive circuit.
 6. The wirelesspower interface of claim 1, wherein the control module is configured toenable the at least one of the plurality of coils based on theelectro-magnetic coupling between the first coil and the at least one ofthe plurality of coils by: coupling the at least one of the plurality ofcoils as an antenna to a transmit circuit and a receive circuit.
 7. Awireless power interface comprises: a plurality of coils configured toderive wireless power, wherein each of the plurality of coils has adifferent orientation with respect to at least one axis of amulti-dimensional axis system; and a control module configured to enableat least one of the plurality of coils based on electro-magneticcoupling between the at least one of the plurality of coils and at leastone coil of a wireless power device.
 8. The wireless power interface ofclaim 7, wherein each of the plurality coils comprises: at least oneplaner winding of a first geometry and of a first size, wherein the atleast one coil of the wireless power device includes at least one planerwinding of the first geometry and of a second size.
 9. The wirelesspower interface of claim 7, wherein the control module is configured toenable the at least one of the plurality of coils based on theelectro-magnetic coupling between the at least one of the plurality ofcoils and the at least one coil of the wireless power device by:providing a transmit signal to one of the plurality of coils; measuringa response from the at least one coil of the wireless power device viathe at least one of the plurality of coils; comparing the response witha response threshold; when the response compares favorably with theresponse threshold, utilizing the at least one of the plurality of coilsto derive power via the electro-magnetic coupling; when the responsecompares unfavorably with the response threshold, determining whethereach of the plurality of coils has been tested; and when each of theplurality of coils has not been tested, repeating the providing, themeasuring, and the comparing for another one of the plurality of coils.10. The wireless power interface of claim 7, wherein the control moduleis configured to enable the at least one of the plurality of coils basedon electro-magnetic coupling between the at least one of the pluralityof coils and the at least one coil of the wireless power device by:providing a transmit signal to a first set of the plurality of coils,wherein an electro-magnetic field created by a coil of the first set ofthe plurality of coils has minimal interference with an electro-magneticfield created by another coil of the first set of the plurality ofcoils; measuring a response from the at least one coil of the wirelesspower device via the first set of the plurality of coils; comparing theresponse with a response threshold; when the response compares favorablywith the response threshold, utilizing the first set of the plurality ofcoils to derive power via the electro-magnetic coupling; and when theresponse compares unfavorably with the response threshold, repeating theproviding, the measuring, and the comparing for a second set of theplurality of coils, wherein a magnetic field created by a coil of thesecond set of the plurality of coils has minimal interference with amagnetic field created by another coil of the second set of theplurality of coils.
 11. The wireless power interface of claim 7, whereinthe control module is configured to enable the at least one of theplurality of coils based on the electro-magnetic coupling between the atleast one of the plurality of coils and the at least one coil of thewireless power device by: coupling the at least one of the plurality ofcoils as a winding of a transformer to a transmit circuit and a receivecircuit.
 12. The wireless power interface of claim 7, wherein thecontrol module is configured to enable the at least one of the pluralityof coils based on the electro-magnetic coupling between the at least oneof the plurality of coils and the at least one coil of the wirelesspower device by: coupling the at least one of the plurality of coils asan antenna to a transmit circuit and a receive circuit.
 13. A wirelesspower device comprises: a transmit section configured to convertoutbound data into transmit near-field communications signals; a receivesection configured to convert received near-field communications signalsinto inbound data; and a wireless power interface coupled to thetransmit section and to the receive section, wherein the wireless powerinterface includes: a plurality of coils configured to derive wirelesspower, wherein each of the plurality of coils has a differentorientation with respect to at least one axis of a multi-dimensionalaxis system; and a control module configured to enable at least one ofthe plurality of coils based on electro-magnetic coupling between the atleast one of the plurality of coils and at least one coil of anotherwireless power device.
 14. The wireless power device of claim 13,wherein each of the plurality coils comprises: at least one planerwinding of a first geometry and of a first size, wherein the at leastone coil of the another wireless power device includes at least oneplaner winding of the first geometry and of a second size.
 15. Thewireless power device of claim 13, wherein the control module isconfigured to enable the at least one of the plurality of coils based onthe electro-magnetic coupling between the at least one of the pluralityof coils and the at least one coil of the another wireless power deviceby: providing wireless power signals to one of the plurality of coils;measuring a response from the at least one coil of the another wirelesspower device via of the plurality of coils; comparing the response witha response threshold; when the response compares favorably with theresponse threshold, utilizing the at least one of the plurality of coilsto derive power via the electro-magnetic coupling; when the responsecompares unfavorably with the response threshold, determining whethereach of the plurality of coils has been tested; and when each of theplurality of coils has not been tested, repeating the providing, themeasuring, and the comparing for another one of the plurality of coils.16. The wireless power device of claim 13, wherein the control module isconfigured to enable the at least one of the plurality of coils based onelectro-magnetic coupling between the at least one of the plurality ofcoils and the at least one coil of the another wireless power device by:providing the transmit near-field communications signals to a first setof the plurality of coils, wherein an electro-magnetic field created bya coil of the first set of the plurality of coils has minimalinterference with an electro-magnetic field created by another coil ofthe first set of the plurality of coils; measuring a response from theat least one coil of the another wireless power device via the first setof the plurality of coils; comparing the response with a responsethreshold; when the response compares favorably with the responsethreshold, utilizing the first set of the plurality of coils to derivepower via the electro-magnetic coupling; and when the response comparesunfavorably with the response threshold, repeating the providing, themeasuring, and the comparing for a second set of the plurality of coils,wherein an electro-magnetic field created by a coil of the second set ofthe plurality of coils has minimal interference with an electro-magneticfield created by another coil of the second set of the plurality ofcoils.
 17. The wireless power device of claim 13, wherein the controlmodule is configured to enable the at least one of the plurality ofcoils based on the electro-magnetic coupling between the at least one ofthe plurality of coils and the at least one coil of the another wirelesspower device by: coupling the at least one of the plurality of coils asa winding of a transformer to the transmit section and the receivesection.
 18. The wireless power device of claim 13, wherein the controlmodule is configured to enable the at least one of the plurality ofcoils based on electro-magnetic coupling between the at least one of theplurality of coils and the at least one coil of the another wirelesspower device by: coupling the at least one of the plurality of coils asan antenna to the transmit section and the receive section.
 19. Thewireless power device of claim 18, wherein the antenna comprises anear-field antenna.
 20. The wireless power device of claim 18, whereinthe antenna comprises a radio frequency (RF) antenna.